i. A standard divi- 

 sion. The line shows 

 depth to plant 



2. After one year's 



growth of a properly 



planted division 



3. Double standard division 



group with base of flower 



stalk showing in centre 



4. A two-year group that 



has flowered. The withering 



old flower stalk is shown 



THE GROWING WAYS OF BEARDED IRIS 



A. C. ARNY 



University of Minnesota 



Success and Satisfaction from Understanding Methods of Development — Why Deep 

 Planting Prevents Flowering — Better Business Relationships Between Buyer and Seller 



jSIDE from flowering time when, of course, the bloom 

 on slender stalks focuses attention upon itself, the 

 leaves of the Iris are conspicuously interesting as 

 they grow in the garden. These leaves are attached 

 at their bases to much thickened portions which vary some- 

 what in shape according to the variety, but are usually elon- 

 gated. 



This thickened portion growing partly above and partly below 

 the ground is a modified stem correctly called a rootstock or 

 rhizome. Besides being a means of spreading the plant in an 

 ever widening circle, these rhizomes are food storehouses like 

 the tuber of the common Potato though differing in that they 

 bear true leaves while tubers bear only rudimentary leaves, 

 called scales, with buds in their axils. Under ordinary circum- 

 stances, the Iris rhizome persists for more than a year while the 

 corm or solid bulb of such plants as Cyclamen, Gladiolus, or 

 Crocus is used up annually. From the portion below the 

 surface of the ground (as indicated by the line in the 

 accompanying photograph) true roots grow outward and 

 downward branching as they go. 



A true bulb, as in Lilies and Hyacinths, consists of a solid stem 

 with the main parts made up of thickened leaves and has little 

 resemblance to the rhizome of the Iris. 



The Natural Position of the Rhizome 



APPROXIMATELY the same position in the soil and on its 

 surface as ducks take on the surface of the water, is the 

 natural one for the Iris rhizome. In this position, exposed to the 

 sun which toughens their outer portions, the rhizomes proba- 

 bly withstand disease better than when entirely covered with 

 earth. 



If, when setting out, the upper surface of the Iris rhizome 

 is left about level with the surface of the compacted soil, it will 

 be in about the right position when the soil has settled thor- 

 oughly. If set much deeper and anchored there by true roots, 

 then the main efforts of the plant are perforce directed toward 

 regaining its proper position and, while doing this, it cannot 

 produce bloom and is said by its owner to be "sulking." 



Rhizomes become anchored securely in the position in the 

 soil where they are planted and cannot change that position 

 except as they send out branches from the eyes which carry 

 the new parts of the plants up to the surface. The food ma- 



terial of the too deeply planted rhizome is spent in elongating 

 the branches in order that the plant may grow up to a 

 natural position. 



Plants shown in Figs. 7 and 10 are the same age as those shown 

 in Figs. 1 and 2 and their much smaller size and less vigorous 

 growth is due entirely to the fact that the rhizomes from which 

 they grew were planted too deeply. This is shown plainly at 

 A in Fig. 5 where, from the rhizome underneath the soil, 

 branches pushed upward, and at the surface of the soil the new 

 true root systems have developed. At B can be seen, rather 

 indistinctly, a young rhizome which is too far beneath the sur- 

 face of the soil and must spend time and energy growing up 

 through the soil to the position reached by the other two. 

 After it has spent most of the growing season reaching the na- 

 tural position, little time will be left for it to become established 

 and make a vigorous growth. It also will be a weakling like the 

 other two. Even where the rhizome is in fairly good position 

 some branches may be too deep beneath the surface. 



Two Views of the Cycle of Development 



THE cycle of development in the Bearded Irises may be 

 either (1) where the plants are not divided for several 

 years after they are set in place resulting in the natural 

 increase besides the production of flowers, or (2) all of the 

 energies of the plants directed toward increase in number by 

 vegetative growth and the production of flowers prevented. 

 The first method may be called the natural cycle and the second 

 the interrupted cycle. 



The rate of growth under either method depends upon the 

 varieties and the tillage methods, as well as the productivity of 

 the soil and the water supply. Under otherwise equal condi- 

 tions such varieties as Monsignor (plants of which variety were 

 the subjects for all the Figures shown in this article) Quaker 

 Lady, Rhein Nixe, Prosper Laugier, Alcazar and many other 

 vigorous growing varieties will make the growth indicated be- 

 low. Edouard Michel, Black Prince, and a few other desirable 

 varieties are much slower of increase. 



The Natural Cycle. Starting with a division of full size 

 for the variety in July or August, 19 19, as shown in Fig, 1, un- 

 der favorable growing conditions, this developed by the latter 

 part of September of the same, year into a one-year group shown 



254 



